Hydrocarbons from a deepwater field (in a sea of at least 100 meters depth) can be produced by the use of a FPU (floating production unit) that carries equipment for removing sand, stones, water, etc. from hydrocarbons that are produced from subsea wells, storing the hydrocarbons, and offloading the stored hydrocarbons to a tanker at intervals. As a field is developed, risers are laid on the sea floor to connect the FPU to additional wells. A large field may be developed over a period of years, as the drilling and completion of wells progresses. Construction vessels that have been used to lay down steel pipe in a pipe string that extends from a well to the FPU, are large and costly, with working rates that may exceed $200,000 per day. A lower cost way to install a pipe string between the FPU and each of a plurality of seafloor well heads over a long period of time, would be of value.